Shaft mounted impellers rotated at high speed by electric motors have been used for grinding, dispersing, deagglomerating, and mixing in solid/liquid systems. Typically, such apparatus have been used as part of a process for the preparation of dispersed pigments useful in products such as paints and inks.
Prior art high speed, high torque dispersion impellers have generally been unable to grind or disperse hard pigments to a 6 plus Hegman index even after hours of operation. The products of such prior art dispersion impellers generally requires further treatment with roller mills, colloid mills, or sand mills, etc., to achieve the desired results (see, Introduction to Paint Technology, 4th edition 1976, published by Oil & Colour Chemists Association, Priory House, 967 Harrow Road, Wembley, Middlesex HAO 2SF, page 147 section, "High Speed Disperser").
U.S. Pat. No. 1,774,910 issued to Whatmough illustrates a rotor made of sandwiched wire gauze segments with projecting ends held in place with bolted side plates.
U.S. Pat. No. 3,894,694 issued to Rothman illustrates a mixing device that depends on the cooperative action of a rotor and a stator.
It is desirable to develop an impeller effective for dispersing and grinding that does not require separate structural elements or have its liquid agitating surfaces severely reduced by its mode of construction.